Riot police escort demonstrators during a protest over the 43 missing Ayotzinapa students, in Mexico City November 20, 2014. [Photo/Agencies]

MEXICO CITY - Protesters and riot police clashed here on Thursday, leading to the arrest of two protesters and the injury of at least two police officers.

Angry students and teachers took to the streets Thursday on the Revolution Day to demand justice in the case of 43 missing students abducted in Mexico's southern state of Guerrero in late September. Sympathizers believed these students had been killed later.

The skirmish between members of the city's police force and scores of masked protesters occurred about 2 pm local time (2000 GMT) at an intersection near the international airport.

About 150 masked protesters, identifying themselves as anarchists, attempted to reach the airport. They were met by some 400 riot police blocking their path.

The attack on the students in the Guerrero town of Iguala on Sept. 26, on the orders of the now imprisoned mayor, has sparked unrest in parts of south and central Mexico, and revealed the extent of drug-related corruption in Guerrero and other states among government officials and security forces.

Protesters Thursday carried banners calling on President Enrique Pena Nieto to step down.

Pena Nieto, who concludes the second year of his five-year term next month, attended a military ceremony Thursday in honor of the armed forces.

"Under no circumstances can we doubt the loyalty ... and dedication of the armed forces," the president said at the ceremony, adding the institution "must not be judged basing on a few elements that could have strayed from their principles."